Liquid aqueous synthetic organic detergent compositions have long been employed for human hair shampoos and as dishwashing detergents for hand washing of dishes (as distinguished from automatic dishwashing, machine washing of dishes). Liquid detergent compositions have also been employed as hard surface cleaners, as in pine oil liquids, for cleaning floors and walls. More recently, they have proven successful as laundry detergents too, apparently because they are convenient to use, are instantly soluble in wash water, and may be employed in "pre-spotting" applications to facilitate removal of soils and stains from laundry upon subsequent washing. Liquid detergent compositions have comprised anionic, cationic and nonionic surface active agents, builders and adjuvants including, as adjuvants, lipophilic materials which can act as solvents for lipophilic soils and stains. The various liquid aqueous synthetic organic detergent compositions mentioned above serve, to emulsify lipophilic materials including oily soils in aqueous media, such as wash water, by forming micellar dispersions and emulsions.
Although emulsification is a mechanism of soil removal, it has been only recently that it was discovered how to make microemulsions which are much more effective than ordinary emulsions in removing: lipophilic materials from substrates. Such microemulsions are described in British Patent Specification No. 2,190,681 and U.S. patent applications Ser. Nos. 06/866,029, 07/085,902, 07/120,250 and 07/267,872 most of which relates to acidic microemulsions useful for cleaning hard surface items such as bathtubs and sinks, which microemulsions are especially effective in removing soap scum and lime scale from them. In U.S. patent application Ser. No. 07/267,872 the microemulsions may be essentially neutral and as such are also thought to be effective for microemulsifying lipophilic soils from substrates. In U.S. patent application Ser. No. 07/313,664 there is described a light duty microemulsion liquid detergent composition which is useful for washing dishes and removing greasy deposits from them in both neat and diluted forms. Such compositions includes complexes of anionic and cationic detergents as surface active components of the microemulsions.
The various microemulsions referred to include a lipophile which may be a hydrocarbon, a surfactant which may be an anionic and/or a nonionic detergent(s), a co-surfactant which may be a poly-lower alkylene glycol lower alkyl ether, e.g. tripropylene glycol monomethyl ether, and water.
Although the manufacture and use of detergent compositions in microemulsion form significantly improves cleaning power and greasy soil removal, compared to the usual emulsions, the present invention improves them still further and also increases the capacity of the detergent compositions to adhere to surfaces to which they have been applied. Thus, they drip or run substantially less than cleaning compositions of "similar" cleaning power which are in normal liquid detergent form. Also, because they will probably form gels with water spontaneously depending upon the amount of dilution with water, with essentially no requirement for addition of any energy, either thermal or mechanical, they are more effective cleaners at room temperature, especially for vertical walls in the gel form and at higher and lower temperatures that are normally employed in cleaning operations than are ordinary liquid detergents and are also more effective than detergent compositions in solution form. The instant compositions can be formed as nonaqueous concentrates which the consumer can use by dilution with water thereby minimizing the amount of waste generated.
Nonaqueous microemulsions of glycerol/sodium dodecyl sulfate/hexanol/alkane, of ethylene glycol/lecithin/decane and of ethylene glycol/sodium dodecyl sulfate/toluene/decanol have been disclosed by Friberg and Co. in Colloids and Surfaces, 24 (1987) 325-336, in Colloid and Polymer Science 262, (1984) 252-253 and in Colloid and Polymer Science 268, (1990) 755-759 respectively. Rico and Lattes claim the formation of microemulsions of formamide/cetyltrimethylamonium bromide/cyclohexane/1-butanol, and of formamide/potassium 2,2,3,3 tetrahydroperfluoroundecanoate/1,1,2,2, tetrahydroperflurohexanol/perflourinated oils in Nouveau Journal de Chimie Vol. 8, No. 7, 1984, p 429 and Journal of Colloid and Interface Science Vol. 102, No. 1, Nov 1984 respectively. Nonaqueous microemulsions of formamide/nonionic surfactants/hydrocarbons and of formamide/didodecyldimethylamonium bromide/toluene have been disclosed by Warnheim and Co. in Journal of Colloid and Interface Science Vol. 131, No. 2, Sept. 1989 and in Progr. Colloid Polym. Sci, 82:271-279 (1990) respectively. Durfler and Co. claim the formation of microemulsions of NN dimethyl formamide/Triton.RTM..times.114/dodecane/n-pentanol, of nitromethane/Triton.RTM..times.114/dodecane/n-pentanol in Tenside Surf, Det. 28 (1991 ), 3, 167-172. The major part of the above mentioned nonaqueous systems are not environmentally safe for consumer use. Due to ingredient toxicity, the use of nonionic surfactants in combination with aliphatic hydrocarbons and a nonaqueous polar solvent has not been disclosed for the formation of microemulsions in nonaqueous solvents which can be used in consumer detergents.
The nonaqueous microemulsion compositions are applicable for use in concentrated household care products and personal care products because they can contain water-incompatible active ingredients such as bleachants and/or enzymes. The nonaqueous microemulsion compositions of the instant invention comprise harmless ingredients as compared to the formamide used by T. Wamheim and M. Sjoberg which could never be used in household or body care products. The instant microemulsion compositions permit the preparation of super concentrated cleaning or conditioning liquid products containing high levels of nonionic surfactants. The instant nonaqueous microemulsion compositions of the instant invention are less temperature-sensitive than aqueous-based microemulsion compositions of the instant invention and therefore have improved storage stability.
The instant nonaqueous microemulsion compositions can form a gel upon a minimum dilution with water and as such are applicable in oral products. A thin layer of the nonaqueous microemulsion could be sprayed or otherwise deposited on the teeth (or on the brush) and subsequently gelled or thickened by the saliva to allow brushing. In accordance with the present invention, a liquid detergent composition, suitable at room temperature or colder or at a higher temperature for pre-treating and cleaning materials soiled with a lipophilic soil, is in a nonaqueous microemulsion form and comprises a nonionic surface active agent, an aliphatic hydrocarbon, a nonaqueous polar solvent and, optionally, a polar co-solvent. The invention also relates to processes for treating items and materials soiled with soils such as a lipophilic soil, with compositions of this invention, to loosen to remove such soil by applying to the locus of such soil on such material a soil loosening or removing amount of the compositions of the microemulsion compositions of the instant invention. The invention is also being in the conversion of the nonaqueous microemulsion liquid composition by the addition of water thereto into a gel or a solution depending upon the amount of the water addition. In another aspect of the invention, lipophilic soil is absorbed from the soiled surface into the nonaqueous microemulsion and then contacted with water so as to convert the microemulsion to solution form.